TO THE GERMAN EDITION This book is addressed to those engineering students who are prepared to work-not to such as are content to refurbish existing designs without taking the trouble to understand the trains of thought and the considerations which are needed in true design work. It is a well-established fact that the beginner, confronted by the simplest of design problems, and lacking a pattern or model to suggest a solution, loses his way in endless trial and error unless given positive guidance. In this book, therefore, the author has drawn on his long teaching experience in an attempt to present in a readily understandable and systematic manner a methodical work­ plan which will enable the beginner practising design problems to reach his objective by a rational route. This approach has the further advantage. con­ firmed by experience, that in adopting it the student will find his interest and pleasure in design work growing, and his self-confidence increasing. Written with the requirements of general mechanical engineering in mind, the book does not deal with the manufacturing methods typical of light precision engineering. To prevent the book from taking on a size which would have detracted from its clear layout and obscured the main principles presented, the numerical tables, graphs, etc. available for reference in pocket books and textbooks have been omitted.